In situ carbothermal reduction/nitridation carbon-nano powder added geopolymer composites

Abstract

Geopolymer was prepared by mixing metakaolin (Al2O3 center dot SiO2) with sodium water glass solution and then the activated carbon nano powder was added the geopolymer. To determine the best composition for carbothermal reduction, one series geoploymer was made with and without carbon by hand. The viscous and homogenous slurry was poured into a mold to obtain bar samples at ambient temperature and cured in a humidity-controlled, constant temperature oven at 50 degrees C for 24 h. The composition of Na2O center dot Al2O3 center dot 4.5SiO(2)center dot 12H(2)O+9C was determined to be best for carbothermal reduction. The carbothermal reduction process of the samples were carried out in an atmosphere controlled tube furnace both under argon (denoted as CTR) and nitrogen (denoted as CTRN) flow of 5 cm(3).min(-1) at temperatures varying between 1450-1550 degrees C for 2h. XRD and SEM analyses were used to determine in situ transformation and morphology of all the products after CTR and CTRN. The results were briefly discussed with respect to possibility of in situ conversion of geopolymers to its carbide and nitride analogues.